Abstract: Litter is a link of material cycle and energy flow in forest ecosystems. It plays a very important role in soil improvement, seedling generation, and soil and water conservation, and it is also essential for shaping C, N and P cycling in forest ecosystems. In this study, five different types of litter from Larix principisrupprechtii forest, Picea crassifolia forest, L. principisrupprechtii and P. crassifolia mixed forest, P. crassifolia and Betula platyphylla mixed forest, and B. platyphylla forest under same site conditions in Qinghai alpine region were selected to study the nutrient contents and stoichiometry of litter. The results showed that with the deepening of litter decomposition layer, the organic carbon content, available phosphorus content, carbon/nitrogen ratio, and carbon/phosphorus ratio in litter of the five stands showed a decreasing trend. P. crassifolia forest litter had higher contents of ammonium nitrogen, nitrate nitrogen, and available phosphorus than the other four stands. The nitrogen contents of broadleaved forest and coniferousbroad forest floor litter were significantly higher than that of coniferous forest and coniferous mixed forest floor litter, and the nitrogen content of broadleaved forest floor litter was 1.23 times as high as that of coniferous forest floor litter. On the contrary, the phosphorus content of coniferous forest litter was 1.26 times as high as that of broadleaved forest litter. In comparison of the stoichiometry of five kinds of floor litter, it could be drawn that litter decomposition of broadleaved forest and coniferousbroad forest was mainly limited by phosphorus, while litter decomposition of coniferous forest and coniferous mixed forest was co-limited by nitrogen and phosphorus.

Key words: interspecific spatial association., spatial pattern, tree seedling